Bearing metal and method of making same



Patented June '18, 1929.

ROBERT JAY SHOEMAKER, OF CHICAGO, ILLINOIS, ASSIGNOR TO s. a :r. METAL oom- PANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

BEARING METAL AND mamon or Maxine same.

No Drawing.

My invention relates to the production of lead base metal alloys and its object is to provide a lead alloy of such character that it mayv be used for bearings, bushings or other like elements where anti-friction surfaces are required or other purposes where a hardened lead is desirable. The invention has particularly in view the production of an anti-friction metal which will be tough and relatively hard, so as to be capable of supporting heavy loads but which at the same time possesses lubricating pro erties.

A further ObJGCt of the invention is to provide an alloy of this character, the alloying metals of which will not'dross or burn out, at least to any undesirable extent, with reasonable care,,either when the ingredient metals are melted up together in compounding or when the alloy is melted in casting operations.

A further object is to provide an alloy, the alloying metals of which will not oxidize When the metal is exposed to the atmosphere.

The alloy of my invention can be made according to twosomewhat different methods, dependent upon whether the product requires primarily and articularly strength, toughness andload caring capacity, where, for example, it is to be usedfor forming the 30 bearing element as. a whole; or requires to .be soldered as, for example, where it is to be used merely as a lining, in which latter case strength isof relatively less importance but the metal must be of such character that it can be made to adhere by soldering to the base to which it is attached.

The method of making the alloy in the form suitable for complete bearings or bushings will be first described.

The primary hardening agent used is sodium and very small quantities of sodium will sufiice to give the lead hardness and toughness rovided the sodium is retained in the lead. I the lead, for example, when the alloy is melted for casting, and to oxidize on exposure of the alloy to the atmosphere. I have discovered that this drossing out can be prevented by the use of small amounts of calcium and aluminum; tin, also, preferably used contributing to the same result, which metals may, therefore, be termed anti-drossing metals.

The method of compounding is preferably carried out as follows: The lead is heated to odium alone tends to dross out of Application filed March 25, 1928. Serial Ilia-97,334. v

a temperature of approximately 1600 ,Fahrenheit, that 1s, so as to raise its temperature to or somewhat above the melting temperature of calcium which is 1400 Fahrenheit.

The melted lead is covered with a supernatant flux or coverin which will not burn at this temperature, which will exclude oxygen and which will-be neutral tothe metals, cal- 0mm and aluminum, to be introduced. The priaferred covering consists of calcium chlor1 e.

The calcium and aluminum are introduced into the lead while .under this covering and the tin also if employed. The melt is then cooled to a temperature somewhat above the melting point of lead, that is, to a temperature, preferably, of between 650 and 700 Fahrenheit. After the calcium and alumi num have been added the'metal may be, poured into ingots and afterward re-heated for the addition of the sodium. In such case the melting of the lead and the addition of the sodium takes place under a supernatant covering consisting of sodium hydrate and rosin, soap, fuel oil or other organic substance which will create a reducing atmosphere or at least exclude oxygen. The sodium hydrate and rosin, or its e uivalent, may be used in substantially equa proportions. The quantity of each may be approximately 1% of the melt. The quantity of sodium hydrate should be small so as to prevent reaction between it and the calcium in the alloy. .Themetallic sodium is put into the flux or supernatant covering and .then

stirred into the molten metal. The temperature rises very considerably, the reaction be- I tweenthe sodium and the other metals being exothermic. The sodium hydrate aids in excluding air from the metals and clarifies the metals by combining with the impurities therein.

The final alloy is then poured into ingots. It can be melted for casting without drossing to any substantial extent.

The alloy may be improved by using small quantities of tin which may be mixed with the lead in the first melting operation as stated.

The ingredient metals are used preferably in the following) proportions by weight.

Sodium 0.3% to 1.0%, the preferred amount being 0.7% to 0.8%. The amount of sodium will vary according to the degree of hardness required. If substantially more hydroxide, during re-melting for casting,

which prevents the drossing out of the sodium. If care is taken in the melting and re-melting operations the amount of calcium used may be small. The amount of calcium in the cast bearing should be not less than 0.1% and, as the cacium acts to a certain extent as a hardening agent, if it is present in a greater amount than approximately 1.0%, the metal will be too hard and brittle. 0.3% to 0.4% of calcium is preferred. If a rigid metal for bearing a heavy load is required there should be at least 0.3% of calcium in the finished article; for metals of lower strength and higher lubricating properties'0.2% of calcium might suflice.

Aluminum from 0.02% to 0.1%. A small amount of aluminum will suflice, and if it is used in uanttities substantially in excess of 0.1% it rosses out and also tends to make the metal viscous.

Tin 2.0% to 5.0%. The tin is anoptional but preferred ingredient. It tends to make the metal more fluid and tougher and to a certain extent aids in preventing the drossi'ng out of the other ingredients. If used in amounts substantially greater than 5% it tends to make the alloy too brittle. If the article itself is heated say to dull-red the tin tends to prevent the burning out of the calcium and sodium.

Lead in an amount to make up 100%.

- The alloy thus formed is-of value for other purposes than for bearings because of its unexpectedly high tensile strength and ductility. For example, an alloy consisting of sodium 0.8%, calcium 0.3%, tin 2.0%, aluminum 0.02%, balance lead, has a tensile strength of 15,000 pounds persquare inch and an. elongation of 7% for a two inch gether and the sodium added with the melt at a temperature approximatelythe melting temperature of lead and covered with a flux, as described, neutral to sodium and of a character to exclude oxygen.

I claim:

1. Method of making a lead-sodium alloy which comprises introducing an anti-drossing metal into the molten lead heated to a point to melt said anti-drossing metal, allowing the melt to cool, and introducing sodium into the same while at a temperature between the melting point of sodium and its vaporizing point.

2. A lead alloy containing from 0.3% to 1.0% sodium, 0.3% to 1.0% calcium, and 0.02% to 0.1% aluminum.

3. A lead allo containing a small quantity of tin and rom 0.3% to 1.0% sodium, 0.3% to 1.0% calcium and 0.02% to 0.1% aluminum.

4. Method of compounding a lead sodium alloy which comprises introducing small quantities of calcium and aluminum into molten lead covered with a molten stratum of a halogen salt of an alkaline earth metal.

ture below the vaporizing point of sodium. I

6. Method of compounding a lead sodium alloy which comprises introducing small quantities of calcium and aluminum into molten lead covered with a molten stratum of calcium chloride. v

ROBERT J AY SHOEMAKER. 

